Opto-electric hybrid modules are typically produced by: individually producing a flexible circuit board including an electric circuit provided on a surface of an insulation layer and covered with a cover lay of an insulative resin, and an optical waveguide including an under-cladding layer, a core and an over-cladding layer stacked in this order; bonding a back surface of the insulation layer of the flexible circuit board to a surface of the over-cladding layer of the optical waveguide with an adhesive agent; and mounting an optical element on a predetermined portion (mounting pads) of the electric circuit. The opto-electric hybrid modules are flexible, and are advantageous for use in a bent state in a small space and for use in a movable portion such as a hinge portion to meet a recent demand for size reduction of electronic devices and the like.
An opto-electric hybrid module as shown in a transverse sectional view of FIG. 5 (see, for example, PTL 1) is also proposed, in which an electric circuit including a plurality of electric circuit body portions 4 and mounting pads 4a is provided on a surface of an under-cladding layer 11 of an optical waveguide W1 to reduce a distance between an optical element 5 and a core 12 for improvement of the optical coupling efficiency between the optical element 5 and the core 12. In the opto-electric hybrid module, the electric circuit body portions 4 are covered with a cladding material layer 13a formed of the same material as an over-cladding layer 13. The cladding material layer 13a has a top surface flush with a top surface of the over-cladding layer 13. In FIG. 5, a reference character 12a designates positioning guides formed of the same material as the core 12 and surrounding mounting pads 4a for positioning electrodes 5a of the optical element 5 with respect to the mounting pads 4a. 